ASME B1.1 Class 2A vs. 1A Studs

[nichol]

While looking at a specific joint issue (a rash of pipe flange leaks - which the main cause was poor bolt up quality), I did pull a random sample of studs from my stock. I found that they met the tolerance of class 1A, but did not meet Class 2A. Has anyone every checked this and seen that this may be causing issues which the integrity of ASME B16.5 300# joints (1 1/2 to 16 NPS in size)

 

[arto]

It doesn't sound like thread tolerance would affect bolt up - maybe it's a material issue?

Also, check out ASME PCC-1-2000 "Guidelines for Pressure Boundary Bolted Flange Joint Assembly."

They have a lot of good stuff on bolt-up techniques that may solve your problems.